Organic photoelectronic device and image sensor

ABSTRACT

Example embodiments relate to an organic photoelectronic device that includes a first electrode, a light-absorption layer on the first electrode and including a first p-type light-absorption material and a first n-type light-absorption material, a light-absorption auxiliary layer on the light-absorption layer and including a second p-type light-absorption material or a second n-type light-absorption material that have a smaller full width at half maximum (FWHM) than the FWHM of the light absorption layer, a charge auxiliary layer on the light-absorption auxiliary layer, and a second electrode on the charge auxiliary layer, and an image sensor including the same.

This application is a continuation of U.S. application Ser. No.14/604,185 filed on Jan. 23, 2015, which claims the benefit of priorityto Korean Patent Application No. 10-2014-0089914 filed in the KoreanIntellectual Property Office on Jul. 16, 2014, the entire disclosure ofeach of which are incorporated herein by reference.

BACKGROUND 1. Field

Example embodiments relate to an organic photoelectronic device and animage sensor.

2. Description of the Related Art

A photoelectronic device typically converts light into an electricalsignal using photoelectronic effects, may include a photodiode, aphototransistor, and the like, and may be applied to an image sensor, asolar cell, and the like.

An image sensor including a photodiode requires high resolution and thusa small pixel. At present, silicon photodiodes are widely used, buttypically exhibit deteriorated sensitivity because of a small absorptionarea due to small pixels. Accordingly, an organic material that iscapable of replacing silicon has been researched.

Accordingly, an organic material that is capable of replacing siliconmay have a high extinction coefficient, or light absorption power, andmay selectively absorb light in a particular wavelength region dependingon a molecular structure, and thus may replace both a photodiode and acolor filter. As a result, the organic material may have an improvedsensitivity and may contribute to higher device integration.

SUMMARY

At least one example embodiment relates to an organic photoelectronicdevice capable of improving wavelength selectivity due to improvedspectral characteristics.

Another example embodiment relates to an image sensor including theorganic photoelectronic device.

According to at least one example embodiment, an organic photoelectronicdevice includes a first electrode. a light-absorption layer on the firstelectrode and including a first p-type light-absorption material and afirst n-type light-absorption material. a light-absorption auxiliarylayer on the light-absorption layer and including a second p-typelight-absorption material or a second n-type light-absorption materialhaving a smaller full width at half maximum (FWHM) than thelight-absorption layer. a charge auxiliary layer on the light-absorptionauxiliary layer; and a second electrode on the charge auxiliary layer.

The light-absorption layer and the light-absorption auxiliary layer maycontact each other.

The second electrode may be disposed at a side where light enters.

The second p-type light-absorption material or the second n-typelight-absorption material may have a smaller FWHM than the FWHM of thelight-absorption layer by about 5 nm or more.

External quantum efficiency (EQE) of the second p-type light-absorptionmaterial or the second n-type light-absorption material at a maximumabsorption wavelength (λ_(max)) may be the same as or higher thanexternal quantum efficiency (EQE) of the light-absorption layer at amaximum absorption wavelength (λ_(max)).

The FWHM of light-absorption layer may be wider than the FWHM of thefirst p-type light-absorption material or the first n-typelight-absorption material.

The second p-type light-absorption material may be the same as ordifferent from the first p-type light-absorption material, and thesecond n-type light-absorption material may be the same as or differentfrom the first n-type light-absorption material.

The second p-type light-absorption material or the second n-typelight-absorption material may be represented by the following ChemicalFormula 1.

In the above Chemical Formula 1,

R^(a) to R¹ may be independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, and

X may be a halogen atom, a halogen-containing group, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C1 to C30 alkoxygroup, a substituted or unsubstituted C1 to C30 aryloxy group, asubstituted or unsubstituted C1 to C30 heteroaryloxy group, asubstituted or unsubstituted silyloxy group, a substituted orunsubstituted amine group, a substituted or unsubstituted arylaminegroup, or a combination thereof.

The second p-type light-absorption material may be the same as ordifferent from the first p-type light-absorption material, and thesecond n-type light-absorption material may be the same as or differentfrom the first n-type light-absorption material.

The first p-type light-absorption material or the first n-typelight-absorption material may be represented by the following ChemicalFormula 2.

In the above Chemical Formula 2,

R^(m) to R^(x) may be independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, and

Y is a halogen atom.

The light-absorption layer and the light-absorption auxiliary layer mayabsorb light in a green wavelength region.

The light-absorption auxiliary layer may have a FWHM of less than orequal to about 90 nm.

The charge auxiliary layer may not substantially absorb light in avisible wavelength region.

The first electrode and the second electrode may be a transparentelectrode, respectively.

According to another example embodiment, an image sensor including theorganic photoelectronic device is provided.

The image sensor may include a semiconductor substrate integrated with aplurality of first photo-sensing devices configured to sense light in ablue wavelength region and a plurality of second photo-sensing devicesconfigured to sense light in a red wavelength region, and the organicphotoelectronic device is on the semiconductor substrate and isconfigured to selectively absorb light in a green wavelength region.

The image sensor may further include a color filter layer including ablue filter configured to selectively absorb light in a blue wavelengthregion and a red filter that is configured to selectively absorb lightin a red wavelength region. The color filter layer may be positionedbetween the semiconductor substrate and the organic photoelectronicdevice.

The first photo-sensing device and the second photo-sensing device maybe stacked.

The image sensor may include a green photoelectronic device that is theorganic photoelectronic device, a blue photoelectronic device configuredto selectively absorb light in a blue wavelength region, and a redphotoelectronic device configured to selectively absorb light in a redwavelength region. The green photoelectronic device, the bluephotoelectronic device, and a red photoelectronic device may be stacked.

According to yet another example embodiment, an electronic deviceincluding the image sensor is provided.

According to at least one example embodiment, an organic photoelectronicdevice includes a first electrode, a light-absorption layer on the firstelectrode, a light-absorption auxiliary layer on the light absorptionlayer and having a smaller full width at half maximum (FWHM) than thelight-absorption layer, a charge auxiliary layer on the light-absorptionauxiliary layer, and a second electrode on the charge auxiliary layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an organic photoelectronicdevice according to at least one example embodiment,

FIG. 2 is a schematic top plan view of an organic CMOS image sensoraccording to at least one example embodiment,

FIG. 3 is a cross-sectional view of the organic CMOS image sensor ofFIG. 2,

FIG. 4 is a schematic cross-sectional view of an organic CMOS imagesensor according to another example embodiment,

FIG. 5 is a schematic top plan view of an organic CMOS image sensoraccording to another example embodiment,

FIG. 6 is a graph showing external quantum efficiency (EQE) depending ona wavelength of organic photoelectronic devices according to Example 1and Comparative Example 1,

FIG. 7 is a graph showing external quantum efficiency (EQE) depending ona wavelength of an organic photoelectronic devices according to Example2 and Comparative Example 2,

FIG. 8 is a graph showing external quantum efficiency (EQE) depending ona wavelength of organic photoelectronic devices according to Example 3and Comparative Example 3.

DETAILED DESCRIPTION

Example embodiments will hereinafter be described in detail, and may beeasily performed by those who have common knowledge in the related art.

However, this disclosure may be embodied in many different forms and isnot construed as limited to the example embodiments set forth herein.

It will be understood that when an element is referred to as being “on,”“connected” or “coupled” to another element, it can be directly on,connected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected” or “directly coupled” to another element,there are no intervening elements present. As used herein the term“and/or” includes any and all combinations of one or more of theassociated listed items. Further, it will be understood that when alayer is referred to as being “under” another layer, it can be directlyunder or one or more intervening layers may also be present. Inaddition, it will also be understood that when a layer is referred to asbeing “between” two layers, it can be the only layer between the twolayers, or one or more intervening layers may also be present.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of example embodiments.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. Like reference numerals referto like elements throughout. The same reference numbers indicate thesame components throughout the specification.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the example term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of exampleembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, example embodiments should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofexample embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined incommonly-used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein. As used herein, expressions such as“at least one of,” when preceding a list of elements, modify the entirelist of elements and do not modify the individual elements of the list.

As used herein, when a definition is not otherwise provided, the term“substituted” refers to one substituted with a substituent being one ofa halogen (F, Br, Cl, or I), a hydroxy group, an alkoxy group, a nitrogroup, a cyano group, an amino group, an azido group, an amidino group,a hydrazino group, a hydrazono group, a carbonyl group, a carbamylgroup, a thiol group, an ester group, a carboxyl group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acid or asalt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2to C20 alkynyl group, a C6 to C30 aryl group, a C7 to C30 arylalkylgroup, a C1 to C4 alkoxy group, a C1 to C20 heteroalkyl group, a C3 toC20 heteroarylalkyl group, a C3 to C30 cycloalkyl group, a C3 to C15cycloalkenyl group, a C6 to C15 cycloalkynyl group, a C2 to C20heterocycloalkyl group, and a combination thereof, instead of hydrogenof a compound.

As used herein, when a specific definition is not otherwise provided,the term “hetero” refers to one including 1 to 3 heteroatoms from N, O,S, and P.

In the drawings, parts having no relationship with the description areomitted for clarity of the embodiments, and the same or similarconstituent elements are indicated by the same reference numeralsthroughout the specification.

Hereinafter, the term ‘combination’ refers to a mixture and/or astacking structure of two or more thereof.

Hereinafter, referring to the drawings, an organic photoelectronicdevice according to at least one example embodiment is described.

FIG. 1 is a cross-sectional view showing an organic photoelectronicdevice according to at least one example embodiment.

Referring to FIG. 1, an organic photoelectronic device 100 according toat least one example embodiment includes a first electrode 10, alight-absorption layer 30 on the first electrode 10, a light-absorptionauxiliary layer 35 on the light-absorption layer 30, a charge auxiliarylayer 40 on the light-absorption auxiliary layer 35, and a secondelectrode 20 on the charge auxiliary layer 40. According to at least oneexample embodiment, one of the first electrode 10 and the secondelectrode 20 is an anode and the other is a cathode. At least one of thefirst electrode 10 and the second electrode 20 may be alight-transmitting electrode, and the light-transmitting electrode maybe made of or include, for example, a transparent conductor such asindium tin oxide (ITO) or indium zinc oxide (IZO), or a metal thin layerof a thin monolayer or multilayer. When one of the first electrode 10and the second electrode 20 is a non-light-transmitting electrode, thenon-light-transmitting electrode may be made of or include, for example,an opaque conductor such as aluminum (Al).

For example, the second electrode 20 may be or include alight-transmitting electrode.

For example, the first electrode 10 and the second electrode 20 may beor include light-transmitting electrodes.

The light-absorption layer 30 may include a first p-typelight-absorption material and a first n-type light-absorption material,and may be configured to absorb light externally to generate excitonsand then to separate the generated excitons into holes and electrons.

At least one of the first p-type light-absorption material and the firstn-type light-absorption material may be or include an organic material,and for example both the first p-type light-absorption material and thefirst n-type light-absorption material may be or include organicmaterials.

The light-absorption layer 30 may include an intrinsic layer (l layer)including the first p-type light-absorption material and the firstn-type light-absorption material, and may be, for example formed byco-deposition and the like. In the intrinsic layer, the first p-typelight-absorption material and the first n-type light-absorption materialmay form a heterojunction (bulk heterojunction).

The intrinsic layer may include the first p-type light-absorptionmaterial and the first n-type light-absorption material in a thicknessratio of about 1:100 to about 100:1. Within the range, they may beincluded in a thickness ratio of about 1:50 to about 50:1, about 1:10 toabout 10:1, or about 1:1. When the first p-type light-absorptionmaterial and the first n-type light-absorption material have acomposition ratio within the range, an exciton may be more effectivelyproduced and a pn junction may be more effectively formed.

The light-absorption layer 30 may be a multilayer including the firstp-type light-absorption material, the first n-type light-absorptionmaterial, or a combination thereof. The light-absorption layer 30 may beor include various combinations, for example, a p-type layer/n-typelayer, a p-type layer/l layer, an l layer/n-type layer, and a p-typelayer/l layer/n-type layer. The p-type layer may include the firstp-type light-absorption material and the n-type layer may include thefirst n-type light-absorption material.

The first p-type light-absorption material and the first n-typelight-absorption material may be configured to absorb light in a visiblewavelength region, and at least one of the first p-type light-absorptionmaterial and the first n-type light-absorption material may beconfigured to selectively absorb light having a desired, oralternatively predetermined wavelength region of a visible wavelengthregion. For example, at least one of the first p-type light-absorptionmaterial and the first n-type light-absorption material may beconfigured to selectively absorb light in a green wavelength region, andthe light in the green wavelength region may have a maximum absorptionwavelength (λ_(max)) of about 500 nm to about 600 nm.

In the light-absorption layer 30, a full width at half maximum (FWHM)indicates a selective absorption degree of light having a desired, oralternatively predetermined wavelength region. Herein, the FWHM is awidth of a wavelength corresponding to a half of maximum externalquantum efficiency (EQE) in an external quantum efficiency (EQE) graph.A small FWHM indicates selective absorption of light in a narrowwavelength region and high wavelength selectivity, and a large FWHMindicates absorption of light in a wide wavelength region and lowwavelength selectivity.

The first p-type light-absorption material and the first n-typelight-absorption material may have different spectrum profiles, and mayhave different FWHMs. The light-absorption layer 30 has a combinedspectrum profile of each spectrum profile of the first p-typelight-absorption material and the first n-type light-absorptionmaterial, and a FWHM of the light-absorption layer 30 may be wider thanthe FWHM of the first p-type light-absorption material or the firstn-type light-absorption material.

The first p-type light-absorption material or the first n-typelight-absorption material may be or include, for example, a compoundrepresented by the following Chemical Formula 2, but is not limitedthereto.

In the Chemical Formula 2,

R^(m) to R^(x) may be independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, and

Y may be a halogen atom.

Y may be, for example, a fluorine atom or a chlorine atom.

For example, the compound represented by the Chemical Formula 2 may beused as the first p-type light-absorption material, and the first n-typelight-absorption material may be or include, for example, a thiophenederivative such as dicyanovinyl-terthiophene (DCV3T), fullerene, afullerene derivative, or an imide compound such as perylene diimide, butis not limited thereto.

For example, when the compound represented by the Chemical Formula 2 isused as the first n-type light-absorption material, the first p-typelight-absorption material may be or include, for example,N,N′-dimethylquinacridone (DMQA), N,N′-dimethyl-2,9-dimethylquinacridone(DMMQA), and the like, but is not limited thereto.

The light-absorption layer 30 may be configured to selectively absorblight in a green wavelength region.

The light-absorption layer 30 may have a thickness of about 1 nm toabout 500 nm, and for example, about 5 nm to about 300 nm. When thelight-absorption layer 30 has a thickness within the above ranges, thelight-absorption layer may more effectively absorb light, moreeffectively separate holes from electrons, and deliver the holes,thereby more effectively improving photoelectric conversion efficiency.

The light-absorption auxiliary layer 35 may contact the light-absorptionlayer 30, and may include a second p-type light-absorption material or asecond n-type light-absorption material.

For example, when the first electrode 10 is a cathode and the secondelectrode 20 is an anode, the light-absorption auxiliary layer 35 mayinclude the second p-type light-absorption material, and when the firstelectrode 10 is an anode and the second electrode 20 is a cathode, thelight-absorption auxiliary layer 35 may include the second n-typelight-absorption material. The second p-type light-absorption materialmay be the same as or different from the first p-type light-absorptionmaterial, and the second n-type light-absorption material may be thesame as or different from the first n-type light-absorption material.

The second p-type light-absorption material or the second n-typelight-absorption material may be selected from materials having smallerFWHMs than the light-absorption layer 30.

As described above, because the light-absorption layer 30 has a combinedspectrum profile of each spectrum profile of the first p-typelight-absorption material and the first n-type light-absorptionmaterial, FWHM of the light-absorption layer 30 may be wider than theFWHM of the first p-type light-absorption material or the first n-typelight-absorption material, and therefore the light-absorption layer 30has lower wavelength selectivity than the first p-type light-absorptionmaterial or the first n-type light-absorption material.

In at least one example embodiment, the second p-type light-absorptionmaterial having a smaller FWHM than the light-absorption layer 30 or thelight-absorption auxiliary layer 35 having the second n-typelight-absorption material may be disposed to be nearer to the electrodewhere light enters than the light-absorption layer 30, and therebywavelength selectivity of the light-absorption layer 30 may becompensated.

For example, the second p-type light-absorption material or the secondn-type light-absorption material may have a smaller FWHM than the FWHMof the light-absorption layer 30 by about 5 nm or more. Within thisrange, the second p-type light-absorption material or the second n-typelight-absorption material may have a smaller FWHM than the FWHM of thelight-absorption layer 30 by about 5 nm to about 50 nm, specificallyabout 10 nm to about 50 nm, and more specifically about 10 nm to about30 nm.

The light-absorption auxiliary layer 35 may have, for example anextinction coefficient that is greater than or equal to about 100,000cm⁻¹, and specifically about 120,000 to 200,000 cm⁻¹ at a maximumabsorption wavelength (λ_(max)).

The light-absorption auxiliary layer 35 may have, for example, anexternal quantum efficiency graph that is less than or equal to about 90nm, for another example, about 30 nm to 90 nm, and for another example,about 50 nm to about 90 nm.

The light-absorption auxiliary layer 35 may maintain or improvephotoelectric conversion efficiency of the light-absorption layer 30,and therefore maximum external quantum efficiency (EQE_(max)) of thesecond p-type light-absorption material or the second n-typelight-absorption material may be the same as or higher than the maximumexternal quantum efficiency (EQE_(max)) of the light-absorption layer30. For example, the maximum external quantum efficiency (EQE_(max)) ofthe second p-type light-absorption material or the second n-typelight-absorption material may be higher than the maximum externalquantum efficiency (EQE_(max)) of the light-absorption layer 30 by about0% to about 30%, for example, by about 0.1% to about 30%, and foranother example, by about 1% to about 30%.

For example, the second p-type light-absorption material or the secondn-type light-absorption material may be represented by the followingChemical Formula 1, but is not limited thereto.

In the Chemical Formula 1,

R^(a) to R¹ may be independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, and

X may be a halogen atom, a halogen-containing group, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C1 to C30 alkoxygroup, a substituted or unsubstituted C1 to C30 aryloxy group, asubstituted or unsubstituted C1 to C30 heteroaryloxy group, asubstituted or unsubstituted silyloxy group, a substituted orunsubstituted amine group, a substituted or unsubstituted arylaminegroup, or a combination thereof.

For example, Table 1 illustrates the extinction coefficient and FWHM,when in Chemical Formula 1, R^(a) to R¹ are independently hydrogen and Xis a group listed in the following Table 1.

TABLE 1 Maximum absorption Extinction coefficient X wavelength (λ_(max))(*10⁴ cm⁻¹) FWHM (nm) Cl 587 15 81 F 582 15 83

581 14 69

581 16 48

579 12 62

580 13 63

579 13 62

580 12 65

584 15 66

583 12 61

575 11 46

575 15 63

581 13 65

The light-absorption auxiliary layer 35 may be configured to selectivelyabsorb light in a green wavelength region.

The light-absorption auxiliary layer 35 may have a thickness of about 1nm to about 200 nm. Within the range, the light-absorption auxiliarylayer 35 may have a thickness of about 5 nm to about 100 nm, and forexample about 5 nm to about 70 nm.

The charge auxiliary layer 40 may be between the second electrode 20 andthe light-absorption auxiliary layer 35, and may be configured to allowholes and electrons separated in the light-absorption layer 30 to easilytransfer to the second electrode 20. The charge auxiliary layer 40 maynot substantially absorb light in a visible wavelength region, andaccordingly does not inhibit absorption of light in a visible wavelengthregion that enters the light-absorption auxiliary layer 35 and thelight-absorption layer 30 from the side of the second electrode 20.

For example, when the first electrode 10 is a cathode and the secondelectrode 20 is an anode, the charge auxiliary layer 40 may be at leastone of a hole injection layer (HIL) for facilitating hole injection, ahole transport layer (HTL) for facilitating hole transport, and anelectron blocking layer (EBL) for preventing electron transport. Whenthe first electrode 10 is an anode and the second electrode 20 is acathode, the charge auxiliary layer 40 may be an electron injectionlayer (EIL) for facilitating electron injection, an electron transportlayer (ETL) for facilitating electron transport, and a hole blockinglayer (HBL) for preventing hole transport.

The charge auxiliary layer 40 may include, for example, an organicmaterial, an inorganic material, or an organic/inorganic material. Theorganic material may be an organic compound having hole or electroncharacteristics, and the inorganic material may be or include, forexample, a metal oxide such as molybdenum oxide, tungsten oxide, nickeloxide, and the like.

The hole transport layer (HTL) may include one of, for example,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS),polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole,N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (TPD),4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA,4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA), and a combinationthereof, but is not limited thereto.

The electron blocking layer (EBL) may include one of, for example,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS),polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole,N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (TPD),4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA,4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA), and a combinationthereof, but is not limited thereto.

The electron transport layer (ETL) may include one of, for example,1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine(BCP), LiF, Alq₃, Gaq₃, Inq₃, Znq₂, Zn(BTZ)₂, BeBq₂, and a combinationthereof, but is not limited thereto.

The hole blocking layer (HBL) may include one of, for example,1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine(BCP), LiF, Alq₃, Gaq₃, Inq₃, Znq₂, Zn(BTZ)₂, BeBQ₂, and a combinationthereof, but is not limited thereto.

In the organic photoelectronic device 100, when light enters from thefirst electrode 10 and/or second electrode 20, and the light-absorptionlayer 30 and the light-absorption auxiliary layer 35 absorb light havinga desired, or alternatively predetermined wavelength region, excitonsmay be produced from the inside. The excitons are separated into holesand electrons in the light-absorption layer 30 and the light-absorptionauxiliary layer 35, the separated holes are transported to an anode thatis one of the first electrode 10 and the second electrode 20, and theseparated electrons are transported to the cathode that is the other ofand the first electrode 10 and the second electrode 20, so as to flow acurrent in the organic photoelectronic device.

The organic photoelectronic device may be applied to various fields, forexample a solar cell, an image sensor, a photo-detector, a photo-sensor,and an organic light emitting diode (OLED), but is not limited thereto.

Hereinafter, an example of an image sensor including the organicphotoelectronic device is described referring to drawings. As an exampleof an image sensor, an organic CMOS image sensor is described.

FIG. 2 is a schematic top plan view of an organic CMOS image sensoraccording to at least one example embodiment, and FIG. 3 is across-sectional view of the organic CMOS image sensor of FIG. 2.

Referring to FIGS. 2 and 3, an organic CMOS image sensor 300 accordingto at least one example embodiment includes a semiconductor substrate110 integrated with a blue photo-sensing device 50B, a red photo-sensingdevice 50R, a transmission transistor (not shown), and a charge storage55, a lower insulation layer 60, a color filter layer 70, an upperinsulation layer 80, and the organic photoelectronic device 100.

The semiconductor substrate 110 may be or include a silicon substrate,and may be integrated with the blue photo-sensing device 50B, the redphoto-sensing device 50R, the transmission transistor (not shown), andthe charge storage 55. The blue photo-sensing device 50B and the redphoto-sensing device 50R may be or include photodiodes.

The blue photo-sensing device 50B, the red photo-sensing device 50R, thetransmission transistor, and/or the charge storage 55 may be integratedin each pixel, and as shown in the drawing, the blue photo-sensingdevice 50B may be included in a blue pixel and the red photo-sensingdevice 50R may be included in a red pixel. The charge storage 55 isshown in only the green pixel, but the blue pixel and red pixel may alsoeach include a charge storage connected with the blue photo-sensingdevice 50B and a charge storage connected with the red photo-sensingdevice 50R.

The blue photo-sensing device 50B and the red photo-sensing device 50Rmay be configured to sense light, the information sensed by thephoto-sensing devices 50B and 50R may be transferred by the transmissiontransistor, the charge storage 55 of the green pixel may be electricallyconnected with the organic photoelectronic device 100 that will bedescribed below, and the information of the charge storage 55 may betransferred by the transmission transistor.

A metal wire (not shown) and a pad (not shown) may be on thesemiconductor substrate 110. In order to decrease signal delay, themetal wire and pad may be made of or include a metal having lowresistivity, for example, aluminum (Al), copper (Cu), silver (Ag), andalloys thereof, but is not limited thereto. However, the metal wire andpad are not limited to the illustrated structure, and the metal wire andpad may be under the photo-sensing devices 50B and 50R.

The lower insulation layer 60 may be formed on the metal wire and thepad. The lower insulation layer 60 may be made of or include aninorganic insulating material such as a silicon oxide and/or a siliconnitride, or a low dielectric constant (low K) material such as SiC,SiCOH, SiCO, and SiOF. The lower insulation layer 60 may have a trenchexposing the charge storage 55. The trench may be filled with fillers.

A color filter layer 70 may be on the lower insulation layer 60. Thecolor filter layer 70 may include a blue filter 70B in the blue pixeland a red filter 70R in the red pixel. In an example embodiment, a greenfilter is not included, but a green filter may be further included.

The upper insulation layer 80 may be on the color filter layer 70. Theupper insulation layer 80 may eliminate a step caused by the colorfilter layer 70 and may smoothen the surface. The upper insulation layer80 and lower insulation layer 60 may include a contact hole (not shown)exposing a pad, and a through-hole 85 exposing the charge storage 55 ofa green pixel.

The organic photoelectronic device 100 may be on the upper insulationlayer 80. The organic photoelectronic device 100 may include the firstelectrode 10, the light-absorption layer 30, the light-absorptionauxiliary layer 35, the charge auxiliary layer 40, and the secondelectrode 20 as described above.

The first electrode 10 and the second electrode 20 may be transparentelectrodes, and the light-absorption layer 30, the light-absorptionauxiliary layer 35, and the charge auxiliary layer 40 may be asdescribed above. The light-absorption layer 30 and light-absorptionauxiliary layer 35 may be configured to selectively absorb light in agreen wavelength region and replace a color filter of a green pixel.

When light enters from the second electrode 20, the light in a greenwavelength region may be mainly absorbed in the light-absorption layer30 and the light-absorption auxiliary layer 35 and photoelectricallyconverted, while the light in the rest of the wavelength regions passesthrough the first electrode 10 and may be sensed in the photo-sensingdevices 50B and 50R.

As described above, the organic photoelectronic device that isconfigured to selectively absorb the light of the green wavelengthregion is stacked, and thus an image sensor may be down-sized. Asdescribed above, the organic photoelectronic device 100 may increasegreen wavelength selectivity due to the light-absorption auxiliary layer35, and may thus decrease crosstalk that is typically generated byabsorbing light except in the green wavelength regions, and increasesensitivity.

FIG. 4 is a schematic cross-sectional view of an organic CMOS imagesensor according to another example embodiment.

An organic CMOS image sensor 300 according to at least one exampleembodiment includes a semiconductor substrate 110 integrated withphoto-sensing devices 50B and 50R, a transmission transistor (notshown), a charge storage 55, an insulation layer 80, and an organicphotoelectronic device 100, similarly to the above example embodimentillustrated in FIG. 3.

However, in the organic CMOS image sensor 300 of this exampleembodiment, the blue photo-sensing device 50B and the red photo-sensingdevice 50R are stacked in a vertical direction and the color filterlayer 70 may be omitted, unlike in the above example embodiment. Theblue photo-sensing device 50B and the red photo-sensing device 50R areelectrically connected with a charge storage (not shown), and theinformation sensed by the photo-sensing device may be transferred by atransmission transistor.

The blue photo-sensing device 50B and the red photo-sensing device 50Rmay be configured to selectively absorb light in each wavelength regiondepending on a stacking depth.

As described above, the organic photoelectronic device that isconfigured to selectively absorb the light of the green wavelengthregion is stacked and the red photo-sensing device and the bluephoto-sensing device are stacked, and thus an image sensor may befurther down-sized. As described above, the organic photoelectronicdevice 100 may increase green wavelength selectivity due to thelight-absorption auxiliary layer 35, and thus decrease crosstalk that isgenerated by absorbing light except in green wavelength region, andincrease sensitivity.

FIG. 5 is a top plan view schematically showing an organic CMOS imagesensor according to another example embodiment.

According to the example embodiment illustrated in FIG. 5, an organicCMOS image sensor has a structure in which a green photoelectronicdevice that is configured to selectively absorb light in a greenwavelength region, a blue photoelectronic device that is configured toselectively absorb light in a blue wavelength region, and a redphotoelectronic device that is configured to selectively absorb light ina red wavelength region are stacked.

In the drawing, the red photoelectronic device, the greenphotoelectronic device, and the blue photoelectronic device aresequentially stacked, but the example embodiments are not limitedthereto, and the red, green, and blue photoelectronic devices may bestacked in various orders.

The green photoelectronic device may be the above organicphotoelectronic device 100, the blue photoelectronic device may includeelectrodes facing each other, a light-absorption layer interposedtherebetween, and including an organic material configured toselectively absorb light in a blue wavelength region, and the redphotoelectronic device may include electrodes facing each other and alight-absorption layer interposed therebetween and including an organicmaterial configured to selectively absorb light in a red wavelengthregion.

As described above, an organic photoelectronic device configured toselectively absorb light in a red wavelength region, an organicphotoelectronic device configured to selectively absorb light in a greenwavelength region, and an organic photoelectronic device configured toselectively absorb light in a blue wavelength region are stacked, andthus may further down-size an image sensor and simultaneously increasesensitivity and decrease crosstalk.

The image sensor may be applied to various electronic devices, forexample a mobile phone, a digital camera, and the like, withoutlimitation.

Hereinafter, the example embodiments are illustrated in more detail withreference to examples but are not limited to these examples.

Manufacture of Organic Photoelectronic Device

Example 1

ITO is sputtered on a glass substrate to form an approximately 100nm-thick lower electrode. Subsequently, molybdenum oxide (MoOx, 0≤x≤3)and aluminum (Al) in a ratio of 1:1 (wt/wt) are thermally deposited onthe lower electrode to form a 5 nm-thick electron transport layer (ETL).Subsequently, on the electron transport layer ETL, a compoundrepresented by the following Chemical Formula 1a (LumTec, LLC) as ap-type light-absorption material, and dicyanovinyl-terthiophene (DCV3T)as a n-type light-absorption material, are co-deposited in a thicknessratio of 1:1, forming a light-absorption layer. On the light-absorptionlayer, a compound represented by the following Chemical Formula 1a isthermally deposited to form a light-absorption auxiliary layer, and amolybdenum oxide (MoOx, 0<x≤3) is thermally deposited thereon, forming acharge auxiliary layer. On the charge auxiliary layer, ITO is sputteredto form a 100 nm-thick upper electrode, manufacturing an organicphotoelectronic device.

Example 2

An organic photoelectronic device is manufactured according to the samemethod as Example 1, except for using fullerene (C60) instead of thedicyanovinyl-terthiophene (DCV3T) as the n-type light-absorptionmaterial.

Example 3

An organic photoelectronic device is manufactured according to the samemethod as Example 1, except for using fullerene (C60) instead of thedicyanovinyl-terthiophene (DCV3T) as the n-type light-absorptionmaterial of the light-absorption layer, and a compound represented bythe following Chemical Formula 1 b instead of the compound representedby the above Chemical Formula 1a for the light-absorption auxiliarylayer.

The compound represented by the above Chemical Formula 1b is synthesizedby the following method.

20.0 g of boron sub-phthalocyanine chloride, 32.0 g of triphenylsilanol,and 14.8 g of trifluoromethanesulfonic acid are heated and refluxed in150 ml of dry toluene for 15 hours. Then, 200 ml of methylene chlorideis added to the resultant, the mixture is filtered, and the filteredsolution is concentrated under a reduced pressure and purified throughsilica gel column chromatography, obtaining a compound represented bythe above Chemical Formula 1b.

Comparative Example 1

An organic photoelectronic device is manufactured according to the samemethod as Example 1, but the organic photoelectronic device does nothave a light-absorption auxiliary layer.

Comparative Example 2

An organic photoelectronic device is manufactured according to the samemethod as Example 2, but the organic photoelectronic device does nothave a light-absorption auxiliary layer.

Comparative Example 3

An organic photoelectronic device is manufactured according to the samemethod as Example 3, but the organic photoelectronic device does nothave a light-absorption auxiliary layer.

Evaluation Evaluation 1: External Quantum Efficiency (EQE) and FWHM

External quantum efficiency (EQE) and FWHM of the organicphotoelectronic devices of Examples 1 to 3 and Comparative Examples 1 to3 are evaluated depending on wavelength.

The external quantum efficiency is measured by using an IPCE measurementsystem. First of all, the measurement system is calibrated by using a Siphotodiode and mounted on the organic photoelectronic devices accordingto Examples 1 to 3 and Comparative Examples 1 to 3, and their externalquantum efficiency is measured in a wavelength range of about 350 to 750nm.

The FWHM is calculated as width of a wavelength corresponding to a halfof maximum external quantum efficiency (EQE_(max)) in the externalquantum efficiency (EQE) graph.

The results are provided in FIGS. 6 to 8 and Table 2.

FIG. 6 is a graph showing external quantum efficiency (EQE) of theorganic photoelectronic devices according to Example 1 and ComparativeExample 1 depending on a wavelength, FIG. 7 is a graph showing externalquantum efficiency (EQE) of the organic photoelectronic devicesaccording to Example 2 and Comparative Example 2 depending on awavelength, and FIG. 8 is a graph showing external quantum efficiency(EQE) of the organic photoelectronic devices according to Example 3 andComparative Example 3 depending on a wavelength.

TABLE 2 Maximum absorption Maximum external wavelength quantumefficiency FWHM (λ_(max), nm) (EQE_(max), %) (nm) Example 1 590 50 110Comparative 570 45 130 Example 1 Example 2 580 57 110 Comparative 580 53130 Example 2 Example 3 570 55 100 Comparative 580 53 130 Example 3

Referring to FIGS. 6 to 8 and Table 2, the organic photoelectronicdevice according to Example 1 shows equivalent or improved externalquantum efficiency and narrowed FWHM, and thus improved wavelengthselectivity compared with the organic photoelectronic device accordingto Comparative Example 1. Likewise, the organic photoelectronic deviceaccording to Example 2 shows equivalent or improved external quantumefficiency and narrowed FWHM, and thus improved wavelength selectivitycompared with the organic photoelectronic device according toComparative Example 2, and the organic photoelectronic device accordingto Example 3 shows equivalent or improved external quantum efficiencyand narrowed FWHM, and thus improved wavelength selectivity comparedwith the organic photoelectronic device according to Comparative Example3.

Evaluation 2: Crosstalk

Crosstalk of the organic photoelectronic devices according to Example 1and Comparative Example 1 is evaluated.

The crosstalk evaluation is performed through simulation by using aLUMERICAL 3D program. Herein, a wavelength region is divided into threeregions of about 440 to 480 nm (blue), about 520 to 560 nm (green), andabout 590 to 630 nm (red), and the optical interference between twoother photoelectric transformation elements of different colors in eachregion is evaluated. In other words, when an integral of a sensitivitycurve of a blue element in the blue region of about 440 to 480 nm isregarded as 100, a relative integral of the sensitivity curves of redand green elements in the blue region of about 440 to 480 nm iscalculated. The obtained value is a crosstalk of the red and greenelements regarding the blue region of about 440 to 480 nm. Likewise,when an integral of a sensitivity curve in the green region of about 520to 560 nm is regarded as 100, a relative integral of sensitivity curvesof the red and blue elements in the green region of about 520 to 560 nmis calculated. This value is crosstalk regarding the green region of thered and blue elements at about 520-560 nm. Likewise, when an integral ofa sensitivity curve in the red region of about 590 to 630 nm is 100, arelative integral of sensitivity curves of the blue and green elementsin the red region of about 520 to 560 nm was calculated. This value iscrosstalk regarding the red region of the blue and green elements atabout 520 to 560 nm. Lastly, the crosstalk values are averaged to obtainan average crosstalk.

The results are provided in Table 3.

TABLE 3 Average crosstalk (%) Example 1 23 Comparative Example 1 29

Referring to Table 3, the organic photoelectronic device according toExample 1 shows greater than or equal to approximately 20% decreasedaverage crosstalk compared with the organic photoelectronic deviceaccording to Comparative Example 1.

While this disclosure has been described in connection with what ispresently considered to be example embodiments, it is to be understoodthat the example embodiments are not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An organic photoelectronic device, comprising: afirst electrode and a second electrode facing each other; alight-absorption layer between the first electrode and the secondelectrode, the light-absorption layer including a first p-typelight-absorption material and a first n-type light-absorption material,the first p-type light-absorption material and the first n-typelight-absorption material forming a heterojunction, and alight-absorption auxiliary layer on one side of the light-absorptionlayer, the light-absorption auxiliary layer including a second p-typelight-absorption material or a second n-type light-absorption material,the light-absorption auxiliary layer having a smaller full width at halfmaximum (FWHM) than the light-absorption layer.
 2. The organicphotoelectronic device of claim 1, wherein the second p-typelight-absorption material or the second n-type light-absorption materialhas a smaller FWHM than a FWHM of the light-absorption layer by about 5nm or more.
 3. The organic photoelectronic device of claim 1, whereinthe second p-type light-absorption material is the same as or differentfrom the first p-type light-absorption material, and the second n-typelight-absorption material is the same as or different from the firstn-type light-absorption material.
 4. The organic photoelectronic deviceof claim 1, wherein the light-absorption auxiliary layer has anextinction coefficient that is greater than or equal to about 100,000cm⁻¹ at a maximum absorption wavelength (λ_(max)).
 5. The organicphotoelectronic device of claim 1, wherein an external quantumefficiency (EQE) of the second p-type light-absorption material or thesecond n-type light-absorption material at a maximum absorptionwavelength (λ_(max)) is equal to or greater than an external quantumefficiency (EQE) of the light-absorption layer at the maximum absorptionwavelength (λ_(max)).
 6. The organic photoelectronic device of claim 1,wherein the second p-type light-absorption material or the second n-typelight-absorption material is represented by the following ChemicalFormula 1, and the first p-type light-absorption material or the firstn-type light-absorption material is represented by the followingChemical Formula 2:

wherein R^(a) to R¹ are independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, X is a halogen atom, a halogen-containing group, a substitutedor unsubstituted C1 to C30 alkyl group, a substituted or unsubstitutedC6 to C30 aryl group, a substituted or unsubstituted C1 to C30 alkoxygroup, a substituted or unsubstituted C1 to C30 aryloxy group, asubstituted or unsubstituted C1 to C30 heteroaryloxy group, asubstituted or unsubstituted silyloxy group, a substituted orunsubstituted amine group, a substituted or unsubstituted arylaminegroup, or a combination thereof,

wherein R^(m) to R^(x) are independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, and Y is a halogen atom.
 7. An organic photoelectronic device,comprising: a light-receiving electrode and an opposing electrode, alight-absorption layer between the light-receiving electrode and theopposing electrode, and a light-absorption auxiliary layer between thelight-receiving electrode and the opposing electrode, wherein thelight-absorption auxiliary layer includes a light-absorption materialconfigured to absorb light in a visible wavelength region.
 8. Theorganic photoelectronic device of claim 7, wherein the light-absorptionlayer and the light-absorption auxiliary layer are configured to absorblight in a green wavelength region.
 9. The organic photoelectronicdevice of claim 8, wherein a FWHM of the light-absorption auxiliarylayer is narrower than a FWHM of the light-absorption layer.
 10. Theorganic photoelectronic device of claim 7, wherein the light-absorptionmaterial of the light-absorption auxiliary layer is represented by thefollowing Chemical Formula 1:

wherein R^(a) to R¹ are independently hydrogen, a substituted orunsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6to C30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a halogen atom, a halogen-containing group, or a combinationthereof, and X is a halogen atom, a halogen-containing group, asubstituted or unsubstituted C1 to C30 alkyl group, a substituted orunsubstituted C6 to C30 aryl group, a substituted or unsubstituted C1 toC30 alkoxy group, a substituted or unsubstituted C1 to C30 aryloxygroup, a substituted or unsubstituted C1 to C30 heteroaryloxy group, asubstituted or unsubstituted silyloxy group, a substituted orunsubstituted amine group, a substituted or unsubstituted arylaminegroup, or a combination thereof.
 11. The organic photoelectronic deviceof claim 7, further comprising a charge auxiliary layer between thelight receiving electrode and the opposing electrode.
 12. An organicphotoelectronic device, comprising: a first electrode and a secondelectrode facing each other; a light-absorption layer between the firstelectrode and the second electrode, the light-absorption layer includinga first p-type light-absorption material and a first n-typelight-absorption material, the first p-type light-absorption materialand the first n-type light-absorption material forming a heterojunction,and a light-absorption auxiliary layer on one side of thelight-absorption layer, wherein a FWHM of the light-absorption auxiliarylayer is narrower than a FWHM of the light-absorption layer.
 13. Theorganic photoelectronic device of claim 12, wherein the light-absorptionauxiliary layer has a FWHM that is less than or equal to about 90 nm.14. The organic photoelectronic device of claim 12, further comprising acharge auxiliary layer on one side of the light-absorption auxiliarylayer.
 15. An image sensor comprising the organic photoelectronic deviceof claim
 1. 16. An electronic device including the image sensor of claim15.
 17. An image sensor comprising the organic photoelectronic device ofclaim
 7. 18. An electronic device including the image sensor of claim17.
 19. An image sensor comprising the organic photoelectronic device ofclaim
 12. 20. An electronic device including the image sensor of claim19.